The Clinical Core is designed to provide human specimens to each of the four Projects in this Proposal. The Clinical Core will also provide statistical expertise and assistance to each of the four Projects concerning interpretation of data obtained from human specimens. The responsibilities of the Clinical Core include: 1) recruitment of volunteers to provide peripheral blood neutrophils for Specific Aim 1 in each Project; 2) recruitment of volunteers to participate in pulmonary endotoxin exposure studies where peripheral blood and lung neutrophils will be obtained and provided for Specific Aim 2 in each Project; 3) identification and recruitment of patients with clinical infections who are at risk for ALI to provide peripheral blood neutrophils for Specific Aim 2 in each Project; 4) identification and recruitment of patients with clinical infections who have ALI to provide peripheral blood and lung neutrophils for Specific Aim 2 in each Project; and 5) providing statistical expertise, consultation, and analysis to each of the Projects. The Clinical Core will be responsible for collecting peripheral blood and for purifying peripheral blood neutrophils that will be provided to each Project. Additionally, the Clinical Core will be responsible for performing bronchoscopy and collecting lung neutrophils and BAL specimens from a) volunteers given endotoxin into the lungs and b) patients with ALI. The Clinical Core will also be responsible for interacting with the University of Colorado Health Sciences Center General clinical Research Center, where the human pulmonary endotoxin exposure studies will be performed. The statistical group within the clinical core will provide design and analysis consultation for all of the projects in this grant. They will help with setting up and transferring databases, maintaining data security, quality control, analysis, data presentation and writing papers. When necessary they will develop new statistical techniques to support the analyses for the projects.